Active Transport : movement of molecules against its concentration gradient (Low → High) across the a plasma membrane. Forceful transportation → requires energy (ATP) * ATP : the small energy carrying molecule that is used within cells of ALL living things. Once the energy is used, it becomes ADP. This is recharged back into ATP inside the mitochondria, during respiration.
Reasons why cells must use active transport, instead of diffusion :
Often a living being requires to uptake molecules that are scarce in their environment
Some molecules cannot be diffused → cell uses "cell-eating" process (Endocytosis)
Protein pumps (a.k.a. carrier proteins) : gate for plasma membrane → allows the molecules to move against concentration gradient → facilitates the rate of active transport of large molecules
Vesicles : bubble-like membranous sac structure that contains fluid or gas Vesicles act as an indirect connection between the rough ER and Golgi apparatus to transport cellular products through following process :
Membrane-bound secretory vesicles bud off from the ER and move to the Golgi apparatus.
The membranous components fuse and the contents of the vesicles are delivered for modification within the Golgi apparatus.
In turn secretory vesicles from the Golgi can leave the cell via exocytosis at the plasma membrane, where again fusion of membrane component occurs.
Vesicles can form into various things: vacuoles, lysosomes, transport vesicles, and etc... Therefore it also has various functions for the cell. They are involved with Buoyancy control, transport, metabolism, and enzyme storage.
Vesicles in a Cell
21. Define Endocytosis & Exocytosis. Draw a series of diagrams to descrive these processes.
Endocytosis {Endo (with-in), cytosis (cell)}
process in which a substances (macromolecules, large particles, small molecules and small cell) gain entry into a cell without passing through the cell membrane. This step subdivided into 3 different types.
Pinocytosis (cell drinking)
Occurs in almost every single cells continuously
Phagocytosis (cell eating)
Results in the ingestion of pariculate matter such as bacteria from ECF (Extracellular Fluid)
The endosome is large, so it is called Phagosome or Vacuole
Only occurs in certain specialized cells such as Neutrophils, Macrophages and Amoeba
Receptor mediated Endocytosis
Some of the integral membrane proteins that a cell displays at its surface
To tranferrin on their surface
Bind tightly to molecule when it encounters a molecule of transferrin
Exocytosis {Exo (outward), cutosis (cell)}
Process in which a membrane-enclosed vesicle packaged in the vesicles are secreted from a cell when vesicle membrane fuses with the plasma membrane
Restores right amount of plasma membrane
Secretion - any molecules dissolved in the fluid contents of these vesicles are discharged into the extracellular fluid
Any integral membrane proteins exposed to the interior surface of the vesicles will now be displated at the cell surface because the vesicles turn inside out as they fuse with the plasma membrane
Shows a section of the wall of a capillary (the smallest of the blood vessels). On the right is the interior or lumen of the capillary. In the middle is the tissue space separating the capillary wall from a nearby muscle cell (left). The small inpocketings of the plasma membrane are clearly seen (arrows
Guinea phagocyte ingests polystyrene beads
22. Distinguish between pinocytosis & Phagocytosis.
Please refer to question 21
23. what is a contractile vacuole? Explain what it does, why and how it works.
Contractile Vacuole is one of organelle (specialized vacuole of eukaryote cells) from protist cell and often found in freshwater protozoaa such as paramecium and amoeba. It forces water out of the pores to reduce osmotic pressure and prevents the cell from bursting
24. Make a special not on sodium-potassium pumps, as we meet these lots all through the IB curriculm.
To pump sodium and potassium ions into the cell
Active transport mechnism
Both sodium and potassium ions are moving from areas of low concentration to areas of high concentration
Usage of energy to power sodium-potassium pumps is Breakdown of ATP
3 sodium ions bind to the protein channel and ATP provides the energy to change the shape the shape of the channel that in turn drives the ions through the channel
One phosphate group from ATP remains for later job
The sodium ions are released on the other side of membrane outside of the cell and the new shape of the channel has a high affinity for potassium ions and two of these ions now bind to the channel
The binding again causes a change in the shape of the protein channel and this conformational change releases the phosphate group on the cytoplasm side
This release allows the channel to revert to its original shape and as a result, the potassium ions are released inside the cell
Active Transport : movement of molecules against its concentration gradient (Low → High) across the a plasma membrane.
Forceful transportation → requires energy (ATP)
* ATP : the small energy carrying molecule that is used within cells of ALL living things. Once the energy is used, it becomes ADP. This is recharged back into ATP inside the mitochondria, during respiration.
Reasons why cells must use active transport, instead of diffusion :
Protein pumps (a.k.a. carrier proteins) : gate for plasma membrane
→ allows the molecules to move against concentration gradient
→ facilitates the rate of active transport of large molecules
Vesicles : bubble-like membranous sac structure that contains fluid or gas
Vesicles act as an indirect connection between the rough ER and Golgi apparatus to transport cellular products through following process :
Vesicles can form into various things: vacuoles, lysosomes, transport vesicles, and etc... Therefore it also has various functions for the cell. They are involved with Buoyancy control, transport, metabolism, and enzyme storage.
21. Define Endocytosis & Exocytosis. Draw a series of diagrams to descrive these processes.
22. Distinguish between pinocytosis & Phagocytosis.
23. what is a contractile vacuole? Explain what it does, why and how it works.
24. Make a special not on sodium-potassium pumps, as we meet these lots all through the IB curriculm.